Thanks Mr Marcelo. I think the question was not appropriately explained. The question is

"126 patients are given lipid lowering therapy and the lipids decreased significantly after treatment. Now these 126 patients have three genotypes (some have AA, some have aA and rest have aa). I need to test the association of genotypes (AA, aA and aa) with the baseline lipid values, percentage change and post treatment values. I mean whether a particular genotype has high baseline values. This can be done easily if the lipid data is parametric but here the lipid data distribution is non-parametric. Which test is to be applied?. Moreover, non-parametric tests only reveal Z score with positive and negative ranks (not mean percentage decrease), so how to test whether a particular genotype has a better response".

thanks